Wearable cardiac defibrillator system controlling conductive fluid deployment

ABSTRACT

In embodiments, a wearable cardiac defibrillator system includes an energy storage module configured to store a charge. Two electrodes can be configured to be applied to respective locations of a patient. One or more reservoirs can store one or more conductive fluids. Respective fluid deploying mechanisms can be configured to cause the fluids to be released from one or more of the reservoirs, which decreases the impedance at the patient location, and decreases discomfort for the patient. In some embodiments an impedance is sensed between the two electrodes, and the stored charge is delivered when the sensed impedance meets a discharge condition. In some embodiments, different fluids are released for different patient treatments. In some embodiments, fluid release is controlled to be in at least two doses, with an intervening pause.

CROSS REFERENCE TO RELATED PATENT APPLICATIONS

This patent application is a continuation of U.S. patent applicationSer. No. 15/614,949 filed on Jun. 6, 2017, which in turn is acontinuation of U.S. patent application Ser. No. 15/384,101, filed onDec. 19, 2016 and issued on Jul. 11, 2017 as U.S. Pat. No. 9,700,733,which in turn is a divisional of copending U.S. patent application Ser.No. 15/135,462, filed on Apr. 21, 2016 and now abandoned, which in turnis a continuation of U.S. patent application Ser. No. 14/161,269, filedon Jan. 22, 2014 and issued on May. 24, 2016 as U.S. Pat. No. 9,345,898,and which in turn claims priority from U.S. Provisional PatentApplication Ser. No. 61/755,919, filed on Jan. 23, 2013, and also fromU.S. Provisional Patent Application Ser. No. 61/841,222, filed on Jun.28, 2013, the disclosures of which are hereby incorporated by referencefor all purposes.

BACKGROUND

When people suffer from some types of heart arrhythmias, the result maybe that blood flow to various parts of the body is reduced. Somearrhythmias may even result in a Sudden Cardiac Arrest (“SCA”). SCA canlead to death very quickly, e.g. within 10 minutes, unless treated inthe interim.

Some people have an increased risk of SCA. People at a higher riskinclude individuals who have had a heart attack, or a prior SCA episode.These people receive the recommendation to receive an ImplantableCardioverter Defibrillator (“ICD”). An ICD continuously monitors theperson's electrocardiogram (“ECG”). If certain types of heartarrhythmias are detected, then the ICD delivers an electric shockthrough the heart.

After being identified as having an increased risk of an SCA, and beforereceiving an ICD, these people are sometimes given a wearable cardiacdefibrillator (“WCD”) system. A wearable defibrillator system typicallyincludes a harness, vest, or other garment for wearing by the patient.The system includes a defibrillator and external electrodes, which areattached on the inside of the harness, vest, or other garment. When theperson wears the system, the external electrodes may then make goodelectrical contact with the person's skin, and therefore can helpmonitor the person's ECG. If a shockable heart arrhythmia is detected,then the defibrillator delivers the appropriate electric shock throughthe person's body, and thus through the heart.

A challenge occurs at the electrode/skin interface. The challenge occursif there were to be a gelled electrode, because the gel can dry out andirritate the person's skin, while undesirably increasing the impedance.

BRIEF SUMMARY

The present description gives instances of wearable cardiacdefibrillator systems, software, and methods, the use of which may helpovercome problems and limitations of the prior art.

In embodiments, a wearable cardiac defibrillator system includes anenergy storage module configured to store a charge. Two electrodes canbe configured to be applied to respective locations of a patient. One ormore reservoirs can store one or more conductive fluids. Respectivefluid deploying mechanisms can be configured to cause the fluids to bereleased from one or more of the reservoirs, which decreases theimpedance at the patient location, and decreases discomfort for thepatient. In some embodiments an impedance is sensed between the twoelectrodes, and the stored charge is delivered when the sensed impedancemeets a discharge condition. In some embodiments, different fluids arereleased for different patient treatments. In some embodiments, fluidrelease is controlled to be in at least two doses, with an interveningpause.

An advantage over the prior art is that the release of fluid iscontrolled in certain situations, and patient discomfort from irritationor electric shock can be minimized.

These and other features and advantages of this description will becomemore readily apparent from the following Detailed Description, whichproceeds with reference to the drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of components of a wearable defibrillator system,made according to embodiments.

FIG. 2 is a diagram showing components of an external defibrillator,such as the one belonging in the system of FIG. 1, and which is madeaccording to embodiments.

FIG. 3 is a diagram showing a set of components of a wearabledefibrillator system made according to embodiments.

FIGS. 4A and 4B are diagrams of an embodiment of a reservoir, such asthe reservoir of FIG. 3, before and after activation.

FIGS. 5A and 5B are diagrams of another embodiment of a reservoir suchas the reservoir of FIG. 3, before and after activation.

FIGS. 6A and 6B are diagrams of a different embodiment of a reservoirsuch as the reservoir of FIG. 3, before and after activation.

FIG. 7 is a diagram of a pump configured to pumping fluid from areservoir to a patient location, according to an embodiment.

FIG. 8 is a diagram of an electrode with an attached fluid retentionstructure, according to embodiments.

FIGS. 9A and 9B are diagrams of one more embodiment of a reservoir suchas the reservoir of FIG. 3, before and after activation.

FIG. 10 is a time diagram of an impedance sensed according toembodiments by a system having components such as the components of FIG.3.

FIG. 11 is a flowchart illustrating methods according to embodiments.

FIG. 12 is a diagram showing a set of components of a wearabledefibrillator system made according to embodiments.

FIG. 13 is a flowchart illustrating methods according to embodiments.

FIG. 14 is a flowchart illustrating methods according to embodiments.

DETAILED DESCRIPTION

As has been mentioned, the present description is about wearable cardiacdefibrillators, software, and methods. Embodiments are now described inmore detail.

A wearable defibrillator system made according to embodiments has anumber of components. One of these components is a support structure,which is configured to be worn by the patient. The support structure canbe any structure suitable for wearing, such as a harness, a vest, one ormore belts, another garment, and so on. The support structure can beimplemented in a single component, or multiple components. For example,a support structure may have a top component resting on the shoulders,for ensuring that the defibrillation electrodes will be in the rightplace for defibrillating, and a bottom component resting on the hips,for carrying the bulk of the weight of the defibrillator. A singlecomponent embodiment could be with a belt around at least the torso.Other embodiments could use an adhesive structure or another way forattaching to the person, without encircling any part of the body. Therecan also be other examples.

FIG. 1 depicts components of a wearable defibrillator system madeaccording to embodiments, as it might be worn by a person 82. A personsuch as person 82 may also be referred to as a patient and/or wearer,since that person wears components of the wearable defibrillator system.

In FIG. 1, a generic support structure 170 is shown relative to the bodyof person 82, and thus also relative to his or her heart 85. Structure170 could be a harness, a vest, one or more belts, a garment, etc., asper the above. Structure 170 could be implemented in a single component,or multiple components, and so on. Structure 170 is wearable by person82, but the manner of wearing it is not depicted, as structure 170 isdepicted only generically in FIG. 1.

A wearable defibrillator system is configured to defibrillate thepatient, by delivering electrical charge to the patient's body in theform of an electric shock. FIG. 1 shows a sample external defibrillator100, and sample defibrillation electrodes 104, 108, which are coupled toexternal defibrillator 100 via electrode leads 105. Defibrillator 100and defibrillation electrodes 104, 108 are coupled to support structure170. As such, many of the components of defibrillator 100 can betherefore coupled to support structure 170. When defibrillationelectrodes 104, 108 make good electrical contact with the body of person82, defibrillator 100 can administer, via electrodes 104, 108, a brief,strong electric pulse 111 through the body. Pulse 111, also known as adefibrillation shock or electrical therapy shock, is intended to gothrough and restart heart 85, in an effort to save the life of person82. Pulse 111 can also be one or more pacing pulses, and so on.

A prior art defibrillator typically decides whether to defibrillate ornot based on an electrocardiogram (“ECG”) of the patient. However,defibrillator 100 can defibrillate, or not defibrillate, also based onother inputs.

The wearable defibrillator system may optionally include an outsidemonitoring device 180. Device 180 is called an “outside” device becauseit is provided as a standalone device, for example not within thehousing of defibrillator 100. Device 180 is configured to monitor atleast one local parameter. A local parameter can be a parameter ofpatient 82, or a parameter of the wearable defibrillation system, or aparameter of the environment, as will be described later in thisdocument.

Optionally, device 180 is physically coupled to support structure 170.In addition, device 180 can be communicatively coupled with othercomponents, which are coupled to support structure 170. Such a componentcan be a communication module, as will be deemed applicable by a personskilled in the art in view of this disclosure.

FIG. 2 is a diagram showing components of an external defibrillator 200,made according to embodiments. These components can be, for example,included in external defibrillator 100 of FIG. 1. The components shownin FIG. 2 can be provided in a housing 201, which is also known ascasing 201.

External defibrillator 200 is intended for a patient who would bewearing it, such as person 82 of FIG. 1. Defibrillator 200 may furtherinclude a user interface 270 for a user 282. User 282 can be patient 82,also known as wearer 82, if conscious. Or user 282 can be a localrescuer at the scene, such as a bystander who might offer assistance, ora trained person. Or, user 282 might be a remotely located trainedcaregiver in communication with the wearable defibrillator system.

User interface 270 can be made in any number of ways. User interface 270may include output devices, which can be visual, audible or tactile, forcommunicating to a user. User interface 270 may also include inputdevices for receiving inputs from users. For example, interface 270 mayinclude a screen, to display what is detected and measured, providevisual feedback to rescuer 282 for their resuscitation attempts, and soon. Interface 270 may also include a speaker, to issue voice prompts,etc. Sounds, images, vibrations, and anything that can be perceived byuser 282 can also be called human perceptible indications. Interface 270may additionally include various controls, such as pushbuttons,keyboards, touchscreens, a microphone, and so on. In addition, dischargecircuit 255 can be controlled by processor 230, or directly by user 282via user interface 270, and so on.

Defibrillator 200 may include an internal monitoring device 281. Device281 is called an “internal” device because it is incorporated withinhousing 201. Monitoring device 281 can monitor patient parameters,patient physiological parameters, system parameters and/or environmentalparameters, all of which can be called patient data. In other words,internal monitoring device 281 can be complementary or an alternative tooutside monitoring device 180 of FIG. 1. Allocating which of the systemparameters are to be monitored by which monitoring device can be doneaccording to design considerations.

Patient physiological parameters include, for example, thosephysiological parameters that can be of any help in detecting by thewearable defibrillation system whether the patient is in need of ashock, plus optionally their history. Examples of such parametersinclude the patient's ECG, blood oxygen level, blood flow, bloodpressure, blood perfusion, pulsatile change in light transmission orreflection properties of perfused tissue, heart sounds, heart wallmotion, breathing sounds and pulse. Accordingly, the monitoring devicecould include a perfusion sensor, a pulse oximeter, a Doppler device fordetecting blood flow, a cuff for detecting blood pressure, an opticalsensor, illumination detectors and maybe sources for detecting colorchange in tissue, a motion sensor, a device that can detect heart wallmovement, a sound sensor, a device with a microphone, an SpO2 sensor,and so on. Pulse detection is taught at least in Physio-Control's U.S.Pat. No. 8,135,462, which is hereby incorporated by reference in itsentirety. In addition, a person skilled in the art may implement otherways of performing pulse detection.

In some embodiments, the local parameter is a trend that can be detectedin a monitored physiological parameter of patient 82. A trend can bedetected by comparing values of parameters at different times.Parameters whose detected trends can particularly help a cardiacrehabilitation program include: a) cardiac function (e.g. ejectionfraction, stroke volume, cardiac output, etc.); b) heart ratevariability at rest or during exercise; c) heart rate profile duringexercise and measurement of activity vigor, such as from the profile ofan accelerometer signal and informed from adaptive rate pacemakertechnology; d) heart rate trending; e) perfusion, such as from SpO2 orCO2; f) respiratory function, respiratory rate, etc.; g) motion, levelof activity; and so on. Once a trend is detected, it can be storedand/or reported via a communication link, along perhaps with a warning.From the report, a physician monitoring the progress of patient 82 willknow about a condition that is either not improving or deteriorating.

Patient state parameters include recorded aspects of patient 82, such asmotion, posture, whether they have spoken recently plus maybe also whatthey said, and so on, plus optionally the history of these parameters.Monitoring device 180 or monitoring device 281 may include a motiondetector, which can be made in many ways as is known in the art. Or, oneof these monitoring devices could include a location sensor such as aGlobal Positioning System (GPS), which informs of the location, and therate of change of location over time. Many motion detectors output amotion signal that is indicative of the motion of the detector, and thusof the patient's body. Patient state parameters can be very helpful innarrowing down the determination of whether SCA is indeed taking place.

System parameters of a wearable defibrillation system can include systemidentification, battery status, system date and time, reports ofself-testing, records of data entered, records of episodes andintervention, and so on.

Environmental parameters can include ambient temperature and pressure. Ahumidity sensor may provide information as to whether it is raining.Presumed patient location could also be considered an environmentalparameter. The patient location could be presumed if monitoring device180 or 281 includes a GPS sensor.

Defibrillator 200 typically includes a defibrillation port 210, such asa socket in housing 201. Defibrillation port 210 includes electricalnodes 214, 218. Leads of defibrillation electrodes 204, 208, such asleads 105 of FIG. 1, can be plugged in defibrillation port 210, so as tomake electrical contact with nodes 214, 218, respectively. It is alsopossible that defibrillation electrodes 204, 208 are connectedcontinuously to defibrillation port 210, instead. Either way,defibrillation port 210 can be used for guiding, via electrodes, to thewearer the electrical charge that has been stored in energy storagemodule 250. The electric charge will be the shock for defibrillation,pacing, and so on. Defibrillation electrodes 204, 208 can be made in anumber of ways, such as by a thin piece of metal foil, such as tin orAg/AgCl, etc.

Defibrillator 200 may optionally also have an ECG port 219 in housing201, for plugging in ECG electrodes 209, which are also known as ECGleads. It is also possible that ECG electrodes 209 can be connectedcontinuously to ECG port 219, instead. ECG electrodes 209 can help sensean ECG signal, e.g. a 12-lead signal, or a signal from a differentnumber of leads, especially if they make good electrical contact withthe body of the patient. ECG electrodes 209 can be attached to theinside of support structure 170 for making good electrical contact withthe patient, similarly as defibrillation electrodes 204, 208.

Optionally and preferably, a wearable defibrillator system according toembodiments also includes a fluid that it can deploy automaticallybetween the electrodes and the patient's skin. The fluid is preferablyconductive, such as by including an electrolyte, for making a betterelectrical contact between the electrode and the patient's skin. Salineand a hydrogel are good examples. Electrically speaking, when the fluidis deployed, the electrical impedance between the electrode and the skinis reduced. Mechanically speaking, the fluid may have higher viscositythan water, such as by being a gel, so that it does not flow away, afterit has been deployed. The fluid can be used for both defibrillationelectrodes 204, 208, and ECG electrodes 209.

The fluid may be initially stored in a fluid reservoir, not shown inFIG. 2, which can be coupled to the support structure. In addition, awearable defibrillator system according to embodiments further includesa fluid deploying mechanism 274. Fluid deploying mechanism 274 can beconfigured to cause at least some of the fluid to be released from thereservoir, and be deployed near one or both of the patient locations towhich the electrodes are configured to be attached. In some embodiments,fluid deploying mechanism 274 is activated responsive to receivingactivation signal AS from processor 230, prior to the electricaldischarge.

Defibrillator 200 also includes a measurement circuit 220. Measurementcircuit 220 receives physiological signals from ECG port 219, ifprovided. Even if defibrillator 200 lacks ECG port 219, measurementcircuit 220 can obtain physiological signals through nodes 214, 218instead, when defibrillation electrodes 204, 208 are attached to thepatient. In these cases, the patient's ECG signal can be sensed as avoltage difference between electrodes 204, 208. Plus, impedance betweenelectrodes 204, 208 and/or the connections of ECG port 219 can besensed. Sensing the impedance can be useful for detecting, among otherthings, whether these electrodes 204, 208 and/or ECG electrodes 209 arenot making good electrical contact with the patient's skin. Thesephysiological signals can be sensed, and information about them can berendered by circuit 220 as data, other signals, etc.

Defibrillator 200 also includes a processor 230. Processor 230 may beimplemented in any number of ways. Such ways include, by way of exampleand not of limitation, digital and/or analog processors such asmicroprocessors and digital-signal processors (DSPs); controllers suchas microcontrollers; software running in a machine; programmablecircuits such as Field Programmable Gate Arrays (FPGAs),Field-Programmable Analog Arrays (FPAAs), Programmable Logic Devices(PLDs), Application Specific Integrated Circuits (ASICs), anycombination of one or more of these, and so on.

Processor 230 can be considered to have a number of modules. One suchmodule can be a detection module 232. Detection module 232 can include aventricular fibrillation detector. Ventricular fibrillation is sometimesabbreviated as “VF”. The patient's sensed ECG from measurement circuit220 can be used by the VF detector to determine whether the patient isexperiencing VF. Detecting VF is useful, because VF often results inSCA.

Another such module in processor 230 can be an advice module 234, whichgenerates advice for what to do. The advice can be based on outputs ofdetection module 232. There can be many types of advice according toembodiments. As one example, a Shock Advisory Algorithm can render theadvice to shock the patient by delivering a charge, as opposed to notshock the patient. Shocking can be for defibrillation, pacing, and soon.

Processor 230 can include additional modules, such as other module 236,for other functions. In addition, if monitoring device 281 is indeedprovided, it may be operated in part by processor 230, etc.

Defibrillator 200 optionally further includes a memory 238, which canwork together with processor 230. Memory 238 may be implemented in anynumber of ways. Such ways include, by way of example and not oflimitation, volatile memories, nonvolatile memories (NVM), read-onlymemories (ROM), random access memories (RAM), magnetic disk storagemedia, optical storage media, smart cards, flash memory devices, anycombination of these, and so on. Memory 238 is thus a non-transitorystorage medium. Memory 238, if provided, can include programs forprocessor 230, which processor 230 may be able to read, and execute.More particularly, the programs can include sets of instructions in theform of code, which processor 230 may be able to execute upon reading.Executing is performed by physical manipulations of physical quantities,and may result in the functions, processes, actions and/or methods to beperformed, and/or the processor to cause other devices or components orblocks to perform such functions, processes, actions and/or methods. Theprograms can be operational for the inherent needs of processor 230, andcan also include protocols and ways that decisions can be made by advicemodule 234. In addition, memory 238 can store prompts for user 282, ifthey are a local rescuer. Moreover, memory 238 can store data. The datacan include patient data, system data and environmental data, forexample as learned by monitoring device 281 and monitoring device 180.The data can be stored memory 238 before it is transmitted out ofdefibrillator 200, or stored there after it is received by it.

Defibrillator 200 may also include a power source 240. To enableportability of defibrillator 200, power source 240 typically includes abattery. Such a battery is typically implemented as a battery pack,which can be rechargeable or not. Sometimes, a combination is used, ofrechargeable and non-rechargeable battery packs. Other embodiments ofpower source 240 can include an AC power override, for where AC powerwill be available, an energy storage capacitor, and so on. In someembodiments, power source 240 is controlled by processor 230.

Defibrillator 200 additionally includes an energy storage module 250,which can thus be coupled to the support structure of the wearablesystem. Module 250 is where some electrical energy is stored in the formof a charge, when preparing it for sudden discharge to administer ashock. Module 250 can be charged from power source 240 to the rightamount of energy, as controlled by processor 230. In typicalimplementations, module 250 includes a capacitor 252, which can be asingle capacitor or a system of capacitors, and so on. As describedabove, capacitor 252 can store the energy in the form of electricalcharge, for delivering to the patient.

Defibrillator 200 moreover includes a discharge circuit 255. Circuit 255can be controlled to permit the energy stored in module 250 to bedischarged to nodes 214, 218, and thus also to defibrillation electrodes204, 208. Circuit 255 can include one or more switches 257. Switches 257can be made in a number of ways, such as by an H-bridge, and so on.

Defibrillator 200 can optionally include a communication module 290, forestablishing one or more wired or wireless communication links withother devices of other entities, such as a remote assistance center,Emergency Medical Services (EMS), and so on. Module 290 may also includean antenna, portions of a processor, and other sub-components as may bedeemed necessary by a person skilled in the art. This way, data andcommands can be communicated, such as patient data, episode information,electrical therapy attempted, CPR performance, system data,environmental data, and so on.

Defibrillator 200 can optionally include other components.

FIG. 3 is a diagram showing a set of components of a wearabledefibrillator system made according to embodiments. A support structurecan be provided, similarly to what was described above for supportstructure 170. A support structure is not shown in the set of FIG. 3, soas to not complicate the drawing. The support structure is intended tobe worn by a patient 382.

An energy storage module 350, potentially similar to energy storagemodule 250, is configured to store an electrical charge. An electrode304 has a lead 305, and another electrode 308 has another lead 305,similarly with similar items described above. Electrodes 304, 308 can becoupled with a support structure, such as support structure 170. Byvirtue of their placement on the support structure, and by how thesupport structure is to be worn by patient 382, electrodes 304, 308 canbe configured to be applied at respective patient locations 324, 328 onskin 383 of the patient. Accordingly, the skin/electrode interface takesplace at patient locations 324, 328. This way, electrodes 304, 308 areconfigured to deliver the charge stored in energy storage module 350 topatient locations 324, 328, when it is otherwise appropriate. Deliveringthe charge is also known as discharging, and a sample discharge 311within the body of patient 382 is also shown.

It should be noted that electrodes 304, 308 can be configured to contactskin 383 directly, or be applied at respective patient locations 324,328 over the patient's clothes. Either way, there is the challenge ofminimizing, and hopefully removing, the hazard of a chemical or heatburn to skin 383 of patient 382. The challenge can be met by reducingthe impedance at the skin/electrode interface, which may be accomplishedby wetting with the appropriate fluid.

An impedance measurement circuit 320, potentially similar to impedancemeasurement circuit 220, can be configured to sense an impedance betweentwo electrodes 304, 308. The sensed impedance is thus the one seen bythe defibrillator via electrodes 304, 308. Once electrodes 304, 308 makegood electrical contact with skin 383, the sensed impedance can betreated as the patient impedance. As will be seen below, releasing afluid may decrease the impedance, in which case the sensed impedance canbe the sensed decreased impedance.

The component set of FIG. 3 further includes a processor 330. Processor330 can be similar to processor 230, and be configured to cause thecharge stored in module 350 to be delivered, when appropriate.

Good electrical contact can be made according to embodiments bydeploying a fluid with low impedance at patient locations 324, 328. Moreparticularly, the set of FIG. 3 may also include a reservoir 354 thatcan be a single reservoir or system of reservoirs. Reservoir 354 can beconfigured to store a fluid 364, and can be coupled to the supportstructure. As such, reservoir 354 is preferably rugged or well insulatedagainst external impact, and is preferably impermeable to liquid andgas, to minimize electrolyte contamination and/or dehydration duringstorage. In some embodiments it is flexible, like a pouch, and it can bea metalized plastic laminate pouch similar to that used in the packagingof medical products as well as food and beverage products. Packagingfrom metalized plastic laminate pouches are made from a low meltingplastic interior layer (such as Low Density Polyethylene) and a thinlayer of metal (e.g. aluminum, etc.). Other outer layers made fromvarious plastics (e.g. polyester, Nylon, Mylar, Polypropylene, etc.) arealso common for various purposes including labeling product withgraphics. The advantages of an electrolyte reservoir constructed frommetalized plastic laminate include being flexible, resisting impactpressures, size (thin), and limiting moisture vapor transmission. Beingthin, reservoir 354 will not press as much against the patient's body.The reservoir can be the appropriate size, such as a capsule or larger.

Fluid 364 is the fluid that will be deployed at one or both of patientlocations 324, 328. Fluid 364 can be an electrolyte, so as to conductelectricity well, and accordingly reduce the impedance sensed byimpedance measurement circuit 320, when it is deployed.

The component set of FIG. 3 further includes a fluid deploying mechanism374, similar to fluid deploying mechanism 274. Fluid deploying mechanism374 may operate responsive to an activation signal AS from processor330. When deploying mechanism 374 operates, it can be configured tocause at least some of fluid 364 to be released from reservoir 364. Thefluid may be released all at once, or in doses. As will be seen, in someembodiments, it is released only as necessary, which may help preservethe ability to repeat as necessary later.

Upon being released, fluid 364 can be deployed near patient location324. This can be accomplished in a number of ways. In some embodiments,reservoir 354 is located near electrode 304, and in fact can be attachedto it. Release can be near electrode 304. A reservoir can include anexit mechanism that has a directing tube; the directing tube can beconfigured to deploy the released fluid towards the desired directionsuch as patient location 324.

Alternately, as shown in FIG. 3, release can be through an opening 384in electrode 304. In other embodiments, a duct 394 is provided betweenreservoir 354 and opening 384, and fluid 364 also travels via duct 394to patient location 324 for deployment. The inclusion of duct 394 in thesystem requires fluid 364 to travel longer for deployment, however.

Accordingly, when fluid 364 is so deployed, it can cause the sensedimpedance to be decreased. In addition, optionally and preferably, aparallel mechanism is provided also for electrode 308, for deployingfluid also at patient location 328.

As a person skilled in the art will be able to discern, there can be anynumber of different designs for combinations of reservoirs, fluids, andfluid deploying mechanisms. Examples are now described.

In some embodiments, fluid deploying mechanism 374 simply buildspressure into reservoir 354, which causes fluid 364 to push its way outof reservoir 354 via an exit mechanism such as mentioned above. The exitmechanism can be merely a path of least resistance in the reservoir.Reservoir 354 could be a plastic capsule with a predefined area of leastresistance, which can burst open when the pressure builds up. Orreservoir 354 could implement the exit mechanism by a valve thatreleases fluid 364, when the latter is above some threshold pressure.The pressure can build up when activation signal AS causes, for example,a burst, such as a small pyrotechnic explosion. Sample particularembodiments are now described.

FIG. 4A shows a reservoir 454 that contains a fluid 464, has an exitmechanism 467, and is operable by a fluid deploying mechanism 474. InFIG. 4B, activation signal AS is received by fluid deploying mechanism474. Gas can thus be directly generated within reservoir 454 by one ormore gas generated propellants, such as nitrous oxide, carbon dioxide,etc. Accordingly, fluid 464 can be released from reservoir 454 via exitmechanism 467.

FIG. 5A shows a reservoir 554 that contains a fluid 564, has an exitmechanism 567, and is operable by a fluid deploying mechanism 574. InFIG. 5B, activation signal AS is received by fluid deploying mechanism574. Remotely stored gas can thus be infused into reservoir 554 via agas cartridge, such as a CO₂ canister, etc. Accordingly, fluid 564 canbe released from reservoir 554 via exit mechanism 567.

FIG. 6A shows a reservoir 654, which includes an elastic membrane 655that defines two chambers. The right chamber has an exit mechanism 667.A fluid 664 is in the right chamber, and a fluid deploying mechanism 674operates in the left chamber. In FIG. 6B, activation signal AS isreceived by fluid deploying mechanism 674. Gas or vapor can be generatedinside the left chamber, and an elastic membrane 655 can push into theright chamber. Methods of gas generation include gas generatedpropellants (e.g. nitrous oxide, carbon dioxide, etc.), a gas cartridge(e.g. CO₂ canister), a substance such as water undergoing a phase change(e.g. liquid-to-gas, etc.), and so on. Accordingly, fluid 664 can bereleased from reservoir 654 via exit mechanism 667.

In some embodiments, the fluid deploying mechanism controls the releaseof the fluid more strictly. An example of such a controlled releasemechanism is when the fluid deploying mechanism includes a pump, whichis configured to pump the fluid out of the reservoir. The pump generatesthe pressure required. In such embodiments, deploying the fluid includespumping. An example is now described.

FIG. 7 shows an embodiment where a reservoir 754 contains a fluid 764.An electrode 704, which can be similar to electrode 304, has an opening784. A pump 777 may pump fluid 764 from reservoir 754 via duct 794 toopening 784. Duct 794 may include the appropriate tubing, and measuresshould be taken to prevent duct 794 from being crimped. Various positivedisplacement pumps with self-priming functionality are suitable for thisapplication. Pump options include a peristaltic pump, a gear pump, arotary screw, and a diaphragm pump, to name a few. A MEMS programmablepump or a piezoelectric pump is also applicable. The main purpose ofpump 777 is to automatically pump the desired amount of fluid 764 to thepatient location when needed. Pumping can be controlled electronically,or triggered, by the processor.

Returning to FIG. 3, in other embodiments, reservoir 354 may simply opennear opening 384, and fluid 364 leaks out. In such embodiments, it ispreferable to use an embodiment of an electrode that includes a fluidretention structure. An example is now described.

FIG. 8 is a diagram of an electrode 810 made according to embodiments.Electrode 810 may be part of a wearable defibrillator according toembodiments, or a part of a monitor-defibrillator or part of anAutomated External Defibrillator (AED).

Electrode 810 includes a conductive pad 822, and a lead 805 similar tolead 305. Conductive pad 822 can include a thin piece of metal foil,such as tin or Ag/AgCl. Other conductors may also be suitable, as wouldbe apparent to one skilled in the art. A woven conductive carbon sheetis also applicable.

Conductive pad 822 optionally includes an opening 884, through whichfluid may be released. The fluid may be released locally, or be guidedby a duct 894, as per the above.

Electrode 810 further includes a fluid retention structure 824 madeaccording to embodiments. Fluid retention structure 824 may be coupled,or attached to conductive pad 822. By its placement relative to othercomponents, fluid retention structure 824 can be configured to be placednear the patient location of electrode 810. Accordingly, if fluid isleaked to fluid retention structure 824, the latter may substantiallyretain it. And the fluid retention structure 824 may be at the patientlocation, thus keeping the fluid there. In addition, due to itsconstitution, fluid retention structure 824 may distribute the fluidsubstantially evenly around the patient location. As such, the fluid maybe caused to be released from the reservoir and be deployed into fluidretention structure 824.

Fluid retention structure 824 may be implemented in different ways. Itcan be thin, flexible, and comfortable against the patient's skin. Forexample, it can be made from any hydrophilic substance that has acharacteristic to absorb and/or adsorb the delivered electrolyte tolower the impedance of the electrode. It may include a sponge such as anopen-cell sponge, and/or a piece of cellulose. Cellulose, like cottonfabric, also works in embodiments. By absorbing/adsorbing the lowviscosity electrolyte fluid, fluid retention structure 824 would preventat least some of the fluid from leaking away from the patient location.To remain at its intended location, fluid retention structure 824 caneven be attached to the support structure. Sewing is a suitable methodto integrate the fluid retention structure to a support structure thatis implemented as a garment.

Another suitable method to attach fluid retention structure 824 to thesupport structure would be to melt the substrates together, for exampleby means of ultrasonic welding or similar application. There may be abenefit for fluid retention structure 824 to be disposable and/orreplaceable, and therefore a method to connect or attach fluid retentionstructure 824 to the support structure would be advantageous. Onepotential solution includes creating a dedicated pocket for slidingfluid retention structure 824 into. Another potential solution would beto attach fluid retention structure 824 to the support structure bymeans of Velcro, snaps or other method.

The released fluid may soak the fluid retention structure by a capillaryeffect and/or a wicking effect. Such effects may decrease the timerequired to saturate the electrode system, and be ready for dischargefaster. High saturation speed can be facilitated by the use of a fabricconstructed from fibers (natural or synthetic, woven or nonwoven) thataid in distributing (wicking) the fluid throughout fluid retentionstructure 824. Moreover, a component may be included for keeping theindividual electrodes hermetically or electrically separated, so as toavoid current shunting between the electrodes.

Further, a combination of pad and fluid retention structure can beimplemented with a structure made by a fabric that includes thinconductive wires woven into the fabric. Conductors with a low impedance(e.g. <1 ohm per square inch) may be used.

An advantage is that, for such releasing, the fluid need not be ejectedforcefully from the reservoir but only leaked. Additionally, the fluidneed not be high viscosity. In fact, it will deploy more easily with alower viscosity. Further, the defibrillation electrodes need not makecontact, or at least full contact, with the patient's skin for the longterm. The person's ECG may be monitored by smaller, ECG electrodes.Moreover, the need to defibrillate the person, or to generate thesuspicion that the person may need defibrillation, may be derivedotherwise.

One more set of sample embodiments is now provided, for a reservoir anda fluid deploying mechanism. It will be appreciated that theseembodiments can be used to implement either fluid being ejected from thereservoir or merely leaking, such as to electrode 810.

FIG. 9A shows a reservoir 954 that contains a fluid 964, has an exitmechanism 967, and is operable by a fluid deploying mechanism 974. Arelease feature is integrated into the walls of reservoir 954. In FIG.9B, activation signal AS is received by fluid deploying mechanism 974.Once activated, and potentially maintained by activation signal AS, therelease feature will produce an orifice for liquid transfer. Externalpressure provided by the support structure and/or walls of reservoir 954will assist in channeling the fluid 964 out of reservoir 954. Potentialrelease feature mechanisms include a) an electric valve (e.g. MEMSdevice, piezoelectric ceramic, solenoid valve, etc.), b) a mechanicaldeformation mechanism (e.g. pierced actuation, reservoir being aninflated balloon, etc.), c) melted substrate (e.g. reservoir housingwall, plastic film, plastic/wax/low-melting alloy plug). A resistiveNichrome wire could be utilized to supply the localized (focused) heatrequired for melting the substrate. Accordingly, fluid 964 can bereleased from reservoir 954 via exit mechanism 967.

Returning to FIG. 3, the stored charge can be delivered to patientlocations 324, 328 depending on whether the impedance sensed byimpedance measurement circuit 320 meets a discharge condition.Accordingly, processor 330 can be configured to cause the stored chargeto be delivered, when the discharge condition is met. This coordinationcan be relevant given that the sensed impedance may be reduced becauseof releasing fluid 364. Examples are now described.

FIG. 10 is a time diagram 1000 of an impedance sensed according toembodiments by a system having components such as the components of FIG.3. The horizontal axis indicates time. The vertical axis indicates thesensed impedance Z, not to scale. The impedance may be sensed multipletimes, and its changing values can be tracked.

The sensed impedance Z could follow time profile 1017. At time T0, i.e.before anything happens, Z could have a value of ZM. The value of ZMcould be infinity for an open circuit, or a very large value if theelectrodes were somehow contacting the patient, but not making goodelectrical contact.

At time T1, the fluid starts being released. It can be all the fluid, orat least some of the fluid but not all. The reason for releasing thefluid could be that a determination has been made that the charge needsto be delivered, or merely that a more reliable ECG needs to be taken onsuspicion that the charge may need to be delivered.

As the fluid is released, the sensed impedance starts to decrease.Optionally, an ECG measurement can be taken via the electrodes, takingadvantage of the reduced impedance.

As the sensed impedance continues to decrease, immediately after timeT2, the sensed impedance has a value below a first threshold Z1. In someembodiments, the discharge condition is that the sensed impedance has avalue below a first threshold. Accordingly, the charge is delivered withthe confidence that the impedance is low enough. If the charge deliverydepends on the instantaneous value of the impedance, the rate ofdecrease of the sensed impedance may also optionally be taken intoeffect for forecasting more exactly the impedance at the time of actualdischarge. The rate of change can include linear and non-linealcomponents.

The first threshold can be set in a number of ways. For example, it canbe a fixed value, such as 500 Ohm. Or it can depend on the intendedtherapy. For example, a determination can be made by the processor thatthe charge needs to be delivered, for a first electrical therapy or asecond electrical therapy. The first electrical therapy could bedefibrillation, and the second electrical therapy could be pacing, suchas anti-bradycardia pacing. The first threshold Z1 can have a firstvalue if the needed delivery of the charge is appropriate for the firstelectrical therapy, and a second value if the needed delivery of thecharge is appropriate for the second electrical therapy.

The values of thresholds, such as the first threshold, can be set in anumber of ways. For example, the first threshold Z1 can be a fixedvalue, such as 500 Ohm.

At time T3, the sensed impedance may settle at a terminal value ZT.Preferably T3 is not very long after T1, and preferably less than aminute. The value ZT would be the sum of the actual patient impedanceZP, plus a difference made from the quality of the contact of theelectrode and the patient, as assisted by the deployment of the fluid.In other words, the difference between ZT and ZP is what is accomplishedby the released fluid. For defibrillation, it is desirable to have thisdifference low (e.g. <3 ohms). For external pacing, it is desirable forthe difference to be higher (e.g. ˜500 ohms). Higher impedance pacingelectrodes distribute the current causing less pain.

In some embodiments, the intent may be to wait until the value settlesto the terminal value ZT, for optimum use of the impedance. Of course,whether the value is settling can be established with a number ofdifferent criteria. For example, the discharge condition can be that thesensed impedance has a value that changes less than a threshold in agiven amount of time. And that threshold could be defined as apercentage of the instantaneous sensed value.

In some embodiments, the discharge condition is that a timeout thresholdhas elapsed since, causing at least some of the fluid to be released.These embodiments can accommodate the possibility that the fluid may beall spent, or the fluid deployment mechanism has been damaged, and soon.

Whether the charge is delivered or not, after some time, the sensedimpedance may start deteriorating, which means increasing again. Thiscould be for a number of reasons, such as the fluid evaporating, dryingoff, or leaking away from the patient locations. For example, at timeT4, the sensed impedance Z2 may have reached a second threshold Z2.Optionally Z2 could have the same value as Z1, but that is not required.In some embodiments, the fluid releasing mechanism can be caused torelease some more of the fluid, if the impedance is sensed to be abovesecond threshold Z2.

It is also possible that the electrodes are not well connected. In thatcase, the discharge condition can again be that a timeout threshold haselapsed.

It is further possible that the fluid has leaked a lot, and in fact hasestablished a conductive bridge outside the patient body. In that case,the sensed impedance can become much less than the minimum possibleimpedance ZP. Accordingly, in some embodiments, a user interface such asuser interface 270 can be configured to output an alert, if the sensedimpedance decreases below an alert threshold ZA. In the case of wearabledefibrillators, patient impedance ZP may have been known in advancerather accurately by the doctor fitting the patient, and alert thresholdZA can be set as a fraction of ZP, for example 70% of ZP.

In some embodiments, a time profile of the sensed impedance, such astime profile 1017, is stored in a memory such as memory 238. Then it canbe exported along with other patient data and event data, analyzed andreviewed.

Moreover, methods and algorithms are described below. These methods andalgorithms are not necessarily inherently associated with any particularlogic device or other apparatus. Rather, they are advantageouslyimplemented by programs for use by a computing machine, such as ageneral-purpose computer, a special purpose computer, a microprocessor,etc.

Often, for the sake of convenience only, it is preferred to implementand describe a program as various interconnected distinct softwaremodules or features, individually and collectively also known assoftware. This is not necessary, however, and there may be cases wheremodules are equivalently aggregated into a single program, even withunclear boundaries. In some instances, software is combined withhardware, in a mix called firmware.

This detailed description includes flowcharts, display images,algorithms, and symbolic representations of program operations within atleast one computer readable medium. An economy is achieved in that asingle set of flowcharts is used to describe both programs, and alsomethods. So, while flowcharts described methods in terms of boxes, theyalso concurrently describe programs.

Methods are now described.

FIG. 11 shows a flowchart 1100 for describing methods according toembodiments. The methods of flowchart 1100 may also be practiced byembodiments of defibrillator systems described above, and the individualoperations of flowchart 1100 may be augmented by, and find explanationin the above descriptions.

According to an operation 1110, a charge is stored. According toanother, optional operation 1120, a determination is made as to whetherthe charge needs to be delivered. If not, the process may return tooperation 1110.

According to another operation 1130, fluid is caused to be released froma reservoir, and be deployed near at least one of two intended patientlocations. The fluid may cause the impedance to be decreased.

According to another, optional operation 1140, an ECG measurement istaken via electrodes. According to another operation 1150, an impedanceis sensed between the electrodes. The impedance may be changing, as wasexplained with reference to FIG. 10. For example, the impedance could bedecreasing, due to the fluid being released at operation 1130.

According to another operation 1160, it is determined whether adischarge condition is met. The discharge condition can be as above. Ifnot, then execution may return to operation 1150, or another operation.

If at operation 1160 it is determined that the discharge condition ismet, then according to another, optional operation 1170, the charge iscaused to be delivered to the patient locations via the electrodes. Thecharge delivery may be according to an intended electrical therapy, andso on.

Additional operations are also possible. For example, an alert may beoutput, if the sensed impedance decreases below an alert threshold.Plus, a time profile of the sensed impedance is stored in a memory, andso on.

FIG. 12 is a diagram showing a set of components of a wearabledefibrillator system made according to embodiments. A support structurecan be provided, similarly to what was described above for supportstructure 170. A support structure is not shown in the set of FIG. 12,so as to not complicate the drawing. The support structure is intendedto be worn by a patient 1282.

An energy storage module 1250, potentially similar to energy storagemodule 250, is configured to store an electrical charge. An electrode1204 has a lead 1205, and another electrode 1208 has another lead 1205,similarly with similar items described above. Electrodes 1204, 1208 canbe coupled with the support structure. By virtue of their placement onthe support structure, and by how the support structure is to be worn bypatient 1282, electrodes 1204, 1208 can be configured to be applied atrespective patient locations 1224, 1228 on skin 1283 of patient 1282.This way, electrodes 1204, 1208 are configured to deliver the chargestored in energy storage module 1250 to patient locations 1224, 1228,when it is otherwise appropriate. A sample discharge 1211 is also shown.It should be noted that electrodes 1204, 1208 can be configured tocontact skin 1283 directly, or be applied at respective patientlocations 1224, 1228 over the patient's clothes.

An impedance measurement circuit 1220, potentially similar to impedancemeasurement circuit 220, can be configured to sense an impedance betweentwo electrodes 1204, 1208. The sensed impedance is thus the one seen bythe defibrillator via electrodes 1204, 1208.

The component set of FIG. 12 further includes a processor 1230.Processor 1230 can be similar to processor 230, and be configured tomake a determination as to whether the patient needs one of a firstelectrical therapy and a second electrical therapy, such asdefibrillation or pacing as described above. Processor 1230 can befurther configured to cause the charge stored in module 1250 to bedelivered, when appropriate, for administering the needed first orsecond electrical therapy.

The component set of FIG. 12 can further make good electrical contact bydistributing fluids, either cumulatively or alternatively. Moreparticularly, the set of FIG. 12 may also include reservoirs 1254, 1255,which can be coupled to the support structure. Reservoirs 1254, 1255 canbe configured to store respective fluids 1264, 1265, which can be asdescribed above. Fluids 1264, 1265 can be similar to each other, ordifferent. Fluids 1264, 1265 can be configured to be deployed at one orboth of patient locations 1224, 1228.

The component set of FIG. 12 further includes fluid deploying mechanisms1274, 1275, similar to fluid deploying mechanism 274. Fluid deployingmechanisms 1274, 1275 may operate responsive to respective activationsignals AS1, AS2 from processor 1230. When deploying mechanism 1274operates, it can be configured to cause at least some of fluid 1264 tobe released from reservoir 1254. Similarly, when deploying mechanism1275 operates, it can be configured to cause at least some of fluid 1265to be released from reservoir 1255.

Upon being released, fluids 1264, 1265 can be deployed near patientlocation 1224. This can be accomplished in a number of ways. In someembodiments, both reservoirs 1254, 1255 are located near electrode 1204,and in fact can be attached to it. Release of first fluid 1264 can benear electrode 1204, or through an opening 1284 through electrode 1204.In other embodiments, a duct 1294 is provided between reservoir 1254 andopening 1284. Additionally, release of second fluid 1265 can be nearelectrode 1204, or through an opening 1285 through electrode 1204. Inother embodiments, a duct 1295 is provided between reservoir 1255 andopening 1285. In some embodiments, openings 1284 and 1285 are merged.

In some embodiments, fluids 1264, 1265 are deployed depending on theneeded electrical therapy that will be administered by the discharge.So, first fluid deploying mechanism 1274 can be configured to cause atleast some of first fluid 1264 to be released from first reservoir 1254and be deployed near at least one of patient locations 1224, 1228, ifthe determination is that the first electrical therapy is needed. Forexample, if the first electrical therapy is defibrillation, first fluid1264 can be a saline solution with a relatively high salt content (e.g.0.9% NaCl) to provide a low impedance.

Similarly, second fluid deploying mechanism 1275 can be configured tocause at least some of second fluid 1265 to be released from secondreservoir 1255 and be deployed near at least one of patient locations1224, 1228, if the determination is that the second electrical therapyis needed. For example, if the second electrical therapy is pacing,second fluid 1265 can be an electrolyte with much less salt than 0.9%NaCl, creating an electrode with a relatively higher impedance.

All the previously mentioned possibilities optionally also apply also tothe embodiments of FIG. 12. For example, one of more of electrodes 1204,1208 may have an attached fluid retention structure, the stored chargemay be delivered after a sensed impedance meets a discharge condition,and so on.

Moreover, a sensor can be provided used to monitor the level (amount) offluid present within the reservoir. The level can be checked duringself-test. As the level drops below the defined threshold, anotification can be provided to the attending physician, a message canbe sent to service for replacement, etc. Further, a reservoir impedancecheck and/or a date code check can further be performed, to ensure theelectrolyte is viable. The reservoir can be packaged and/or soldseparately, or with the electrodes for replacement when used or expired.

FIG. 13 shows a flowchart 1300 for describing methods according toembodiments. The methods of flowchart 1300 may also be practiced byembodiments defibrillator systems described above. In addition, and theindividual operations of flowchart 1300 may be augmented by, and findexplanation in the above descriptions.

According to an operation 1310, charge is stored.

Then a determination may be made as to whether the patient needs one afirst electrical therapy or a second electrical therapy, either one ofwhich may be administered by discharge. So, in some embodiments,according to another operation 1320, it is determined whether thepatient needs a first therapy; if not, then according to anotheroperation 1350, it is determined whether the patient needs a secondtherapy. Again, if not, execution can loop to the same two operations.

If at operation 1320 the first therapy is needed then, according toanother operation 1330, the first fluid is caused to be released from afirst reservoir and be deployed near a patient location. Then, accordingto another operation 1340, the first therapy is administered, andexecution may return to operation 1320.

If at operation 1350 the second therapy is needed then, according toanother operation 1360, the second fluid is caused to be released from asecond reservoir and be deployed near a patient location that could bethe same as the location of operation 1330. Then, according to anotheroperation 1370, the second therapy is administered, and execution mayreturn to operation 1320.

In either case, the charge can be caused to be delivered via theelectrodes for administering the needed one of the available electricaltherapies.

Additional operations are also possible. For example, an impedancebetween the two electrodes may be sensed, and the stored charge can bedelivered after the sensed impedance meets a discharge condition.Additionally, an alert may be output, if the sensed impedance decreasesbelow an alert threshold. Plus, a time profile of the sensed impedanceis stored in a memory, and so on.

FIG. 14 shows a flowchart 1400 for describing additional methodsaccording to embodiments. The methods of flowchart 1400 may also bepracticed by embodiments described above, including by embodiments ofFIG. 3 and FIG. 12. In addition, the individual operations of flowchart1400 may be augmented by, and find explanation in the abovedescriptions.

According to an operation 1410, a charge is stored.

According to another operation 1420, at least some of the fluid iscaused to be released from the one or more reservoirs and be deployednear a certain one of the patient locations. The fluid can be all thesame, or different in different reservoirs.

According to another operation 1430, execution waits for at least oneminute before deploying any more, during which time an ECG may be taken,some of the electrical charge may be delivered, and so on. The patientmay be deemed well for some time, but then not anymore, and so on.

According to another operation 1440, at least some more of the fluid iscaused to be released from the one or more reservoirs, and be deployednear the certain patient location.

Operation 1440 may be repeated after more pauses, and so on. Such isparticularly useful if a patient will need multiple electricaldischarges in a single episode, as may happen in a number of scenarios.Sometimes episodes are prolonged. Defibrillation may need to berepeated. Anti-bradycardia pacing may need to last an hour or more,before help arrives. Embodiments, by being able to replenish the fluid,may sustain the patient better.

Additional operations are also possible. For example, an impedancebetween the two electrodes may be sensed, and the stored charge can bedelivered after the sensed impedance meets a discharge condition.Additionally, an alert may be output, if the sensed impedance decreasesbelow an alert threshold. Plus, a time profile of the sensed impedanceis stored in a memory, and so on.

In the methods described above, each operation can be performed as anaffirmative step of doing, or causing to happen, what is written thatcan take place. Such doing or causing to happen can be by the wholesystem or device, or just one or more components of it. In addition, theorder of operations is not constrained to what is shown, and differentorders may be possible according to different embodiments. Moreover, incertain embodiments, new operations may be added, or individualoperations may be modified or deleted. The added operations can be, forexample, from what is mentioned while primarily describing a differentsystem, device or method.

This description includes one or more examples, but that does not limithow the invention may be practiced. Indeed, examples or embodiments ofthe invention may be practiced according to what is described, or yetdifferently, and also in conjunction with other present or futuretechnologies.

Reference to any prior art in this specification is not, and should notbe taken as, an acknowledgement or any form of suggestion that thisprior art forms parts of the common general knowledge in any country.

A person skilled in the art will be able to practice the presentinvention in view of this description, which is to be taken as a whole.Details have been included to provide a thorough understanding. In otherinstances, well-known aspects have not been described, in order to notobscure unnecessarily the present invention.

Other embodiments include combinations and sub-combinations of featuresdescribed herein, including for example, embodiments that are equivalentto: providing or applying a feature in a different order than in adescribed embodiment; extracting an individual feature from oneembodiment and inserting such feature into another embodiment; removingone or more features from an embodiment; or both removing a feature froman embodiment and adding a feature extracted from another embodiment,while providing the advantages of the features incorporated in suchcombinations and sub-combinations.

The following claims define certain combinations and subcombinations ofelements, features and steps or operations, which are regarded as noveland non-obvious. Additional claims for other such combinations andsubcombinations may be presented in this or a related document.

1-79. (canceled)
 80. A wearable defibrillator system, comprising: asupport structure configured to be worn by a patient; an energy storagemodule configured to store a charge; two electrodes coupled with thesupport structure and configured to be applied to two respective patientlocations of the patient; a reservoir coupled to the support structureand configured to store a fluid; a fluid deploying mechanism configuredto cause at least some of the fluid to be released from the reservoirand be deployed near at least one of the patient locations, so as tocause an impedance between the two electrodes to be decreased; and animpedance measurement circuit configured to sense the decreasedimpedance, and in which the stored charge is delivered to the patientvia the electrodes responsive to a timeout threshold lapsing since atleast some of the fluid has been caused to be released, or responsive tothe sensed impedance meeting a discharge condition prior to the timeoutthreshold lapsing, the discharge condition being distinct from thetimeout threshold lapsing.
 81. The system of claim 80, in which thedischarge condition is that the sensed impedance has a value below afirst threshold.
 82. The system of claim 80, in which the dischargecondition is that the sensed impedance has a value that changes lessthan a threshold in a given amount of time.
 83. The system of claim 80,in which the reservoir includes an exit mechanism that has a directingtube.
 84. The system of claim 80, in which the fluid deploying mechanismincludes a pump configured to pump the fluid out of the reservoir. 85.The system of claim 80, in which an ECG measurement is taken via theelectrodes.
 86. The system of claim 80, further comprising: a memory,and in which a time profile of the sensed impedance is stored in thememory.
 87. A non-transitory computer-readable storage medium storingone or more programs which, when executed by a defibrillator systemincluding an energy storage module, an impedance measurement circuit,two electrodes configured to be applied to two respective patientlocations of a patient, a reservoir containing fluid, and a fluiddeploying mechanism, they result in operations comprising: storing acharge; causing at least some of the fluid to be released from thereservoir and be deployed near at least one of the patient locations, soas to cause an impedance between the two electrodes to be decreased;sensing the decreased impedance; and causing the charge to be deliveredto the patient via the electrodes responsive to a timeout thresholdlapsing since at least some of the fluid has been caused to be released,or responsive to the sensed impedance meeting a discharge conditionprior to the timeout threshold lapsing, the discharge condition beingdistinct from the timeout threshold lapsing.
 88. The medium of claim 87,in which the discharge condition is that the sensed impedance has avalue below a first threshold.
 89. The medium of claim 87, in which thedischarge condition is that the sensed impedance has a value thatchanges less than a threshold in a given amount of time.
 90. The mediumof claim 87, in which executing the one or more programs further resultsin: taking an ECG measurement via the electrodes.
 91. The medium ofclaim 87, in which executing the one or more programs further resultsin: outputting an alert if the sensed impedance decreases below an alertthreshold.
 92. A method for a defibrillator system including an energystorage module, an impedance measurement circuit, two electrodesconfigured to be applied to two respective patient locations of apatient, a reservoir containing fluid, and a fluid deploying mechanism,the method comprising: storing a charge; causing at least some of thefluid to be released from the reservoir and be deployed near at leastone of the patient locations, so as to cause an impedance between thetwo electrodes to be decreased; sensing the decreased impedance; andcausing the charge to be delivered to the patient via the electrodesresponsive to a timeout threshold lapsing since at least some of thefluid has been caused to be released, or responsive to the sensedimpedance meeting a discharge condition prior to the timeout thresholdlapsing, the discharge condition being distinct from the timeoutthreshold lapsing.
 93. The method of claim 92, in which the dischargecondition is that the sensed impedance has a value below a firstthreshold.
 94. The method of claim 92, in which the discharge conditionis that the sensed impedance has a value that changes less than athreshold in a given amount of time.
 95. The method of claim 92, furthercomprising: taking an ECG measurement via the electrodes.
 96. The methodof claim 92, further comprising: outputting an alert if the sensedimpedance decreases below an alert threshold.
 97. The method of claim92, in which a time profile of the sensed impedance is stored in amemory.